Centralizer for rock drills



Nov. 2,v 1943'. P. H. NAsT cENTRALIzER FOR ROCK DRILLs 3 3 sheets-sheet2v Filed Sept. 22, 1942 INVENTOR 19u/L H. A4452 BY v Patented Nov. 2,1943 l ff UNITED srAfrEs Rar-'Enr OFFICE I 'n Passaic? A v .CENTRALIZERFon ROCK DRlLLs frnuln. Nasepetrda, Mich., assigner to. 'chicago'Pneumatic Tool Company, TN'ewfYok, "N. Y., a .corporationl'of New Jersey"Applicationseptember z2, 1942, 'seri-.t1 m4459259 l.'Zlhis inventionrelates` tocentralizer 1 apparatus ofthe kind provided in rockdrills ofthe drifter type to guidethe .drill steel when starting. ahole. vIn adrifter the .drillis `supported ona shell mount and advances relatively.thereto `as it drives the .working steel vthrough .the rock. The [steelY ordinarily is supportedand .guided .only by .the chuck yparts ofthedrill. 'This does .notmake for an alignment .suiiciently rigidtofpreventthesteel from being deflected .out of. its proper .course when startinga hole inan irregularsurface.A As a-re sult'it is the practicet'oattachtothefront of the 'shell an auxiliary guide means ori centralizerwhich furnishes a bearing for .thesteel in ad- -vance of ther drill.According v.to Athepreferred construction of a centralizar itlcornprisesessentially4 a pair of guide' ,arms :supported V.oni a f bodyportionfor pivotalmovement tdand-.from a position in which theycombinesubstantiallyitosurround `the vdrill'stel with'a closeft.Movement 'of the centralizer arms" from .effective positionisnecessarykinV Order not to restrict the advance .f the drill and isgenerally accomplished'byA the drill itself which vrocks the` arms outof 'its .path

after a travel suiiicient Itostart the .steel along;

justment. v

.The present invention contempla-resa centralizer construction which isbroadly new although;

retaining the essential elements. and'general mode of operation'r ofprior. art devices. j

One object of the invention .is to makepossible a more positiveontrolo'f the centralizer arms.

Another object is to. simplify vthe 'structure o'f the .centralizerounitthrough a reduction `in the numberof parts, while makinguse o'f'a'construction lending ruggedness andllong life` to" the unit. 'A furtherobject 'of th'einventionis'to 'embody inthe centralizer anoil'reservoirand ports "leading therefrom tofriction bearing surfaces intthe unit;vfor purposes tof lubrication.

Incarrying out these "Objects a drillsteel'centralizer has resultedwhichcomprises 'aibddyhaving a projecting stub-shaftand abore constituting anoil'reservoir, a-'guideplate'and atrunn'ion 5 plate slidably mountedonthe shaft, centralizer arms pivotally mountedvon angularly 'disposedtrunnions on the trunnion plata-reaction surfaces on the guideplate-against which f'theiarms bear in 'pivoting onthetrunnioniplata'fcams effecting position of adjustment.

.companying drawings, wherein:

i jOther.objectsandstructural details ofthe invention will.beapparentfrom the Vfo1lowing..de

scription when fread in. conjunctionwith the acvthearmsfin full linesastheyappearwhen closedv to .effective position` and `in dotted .lines .asthey .appear 4when' opened .to i ineffective position;

Fign`2 is-a viewlike Fig. .1 but inside elevation; l-Fig.l`3 .is afragmentary verticallongitudinal .sec-

.tiontakenthrough the .body portion, showingthe oiLreservoir andcommunicating ports;

.Fig ..7 iis-;a-.detail.view,l.in perspective, of .the

trunnionplate; and L, I l

z Figs. -.8 :to .11are..detail views of rone of the centralizar-arms,t1i!ig.:],0 being in cross-section :takenalongthelineiD-lof Fig9. ll"Referringffto Figs. .1v1-and 2, fragmentary-portions-of`tlfre-drillfthe working-steel, and the vshell .mount are-indicatedlrespectively at v2i), -2 I and 122. Alsoeshownnis 'apart of thefeedscrew 23, -this being arotatable screwthreaded shaft extending.lengthwise --of -the vshell and operatively `-engaged with #the .drill--tol `advance-and retract it towardandrfromfthe-work. n

Cenventionallyfthefront of-th'e shell 22 is closed .by an:end=.p1ateprovidinga bearing for'the front of the feed -screw.f23'.- Invthepresent'instance, this.-plateis-embodiedin an element 24 which servesalso `v`as Ithesupport-.orslcnody portion of the'drillnsteel'ceritralizenv The 'body 24 is fastened :to thefshell by fthrough side rods y25, and, midway .betweenthe rods ata ypoint aboveitscentral'axis, is :formed *Withia -bore T26 adapted to receive Athe'end'of l:thefeed screw `23:-(see Figs. 3 and 6,) A bushing 21 'inthefbore'formsthe `bearing surface within-which'the: screw rotates. c f

'Projectingfforwardly lfrom y'the 'fbody porti-on '24 lis-an integrallyformed'stub shaft "23. Sur- -mouting the rstub AAsl'iaft `arev controlyelements z of the '.'ceritralizer assembly, includingja 'combina'-tionguidefandreaction plate' 29 and y:a'trunnion plate 31.' 'The plate29occupie's .the inside poe sition ron-the fsh'aft28 abutting afb'oss3l) on l'the vfront face of the body 24. ^In jorder Vtol position vtheguide plate '.rotatvely, ia recess 40 isV formed ftherein adapted `tovregistery with the bor'e '26 'inlthe'body-ll. As vshow'n-inlig. 3, therecess T4@ "drill, 'angular jaws 36 on thei plate 29, and, incrossaction plate 29.

closes the bore 26 at the point where it breaks through the body 24, andreceives the inner end of bushing 21 which thus acts as a dowel pin. Thetrunnion plate 3| lies in front of the plate 29 and, as shown in Figs. 5and '7, has flat side surfaces 50 inclining rearward and inward towardthe axis of the shaft 28. Oppositely disposed trunnionsj32 wextend atright angles from the surfaces 50 and therefore at any oblique anglewith respect to each other and to the longitudinal axis of the trunnionplate. ring to Fig. 4 the trunnions 32 are surrounded by bushings 33 andprovide a pivotal mounting for centralizer arms 34. As shown alsoinFigs:v

8 to 11 the centralizer arms curve upward and inward from their baseportions 34a toward the axis of the drill steel andterminate in concavesurfaces 35. of the separate arms provide a restricted passage for thedrill steel, preventing its departure from thel longitudinal linedefined by the axis of the The base portions y34|@ are embraced bysection, have a rect'ai'igularV shape,V the sides "thereof parallelingthe respective sloping surfaces 50 of the trunnion plate ,3|. The jaws3S prevent the centralizerarms from slipping off thehtrunnions 32 andfurtherare of aidV in holding the armsflrmly against the drillsteel. Inthe plate 29 at ,the base of eachjaw 36is formed a groove 3'! in whichthe edge of the associated vcentralizer farm is engaged( `to prevent`rotary movement of the trunnion plate. The bottom of the groove is flatand complementary surfaces are formed on the edge of the lcentraliser`arm (see Fig. 9), these surfaces beingindicatedY at 38 and 39 connectedby a rounded area 4|.

Ysteel and drops the arms outof the path of the drill. In the uprightclosed orfeffective position ofthe arms vthe'surfaces 381 thereon arepresented tothe guide plate 29 while movement to ineffective positionbrings the surfaces 39 to cooperative relation withVK the guide plate,Awithr the area 4| acting as a camion the plate to enforce an axialmovement ofthe trunnion plate 3 The plate 23 thus acts as a reactionelement against `which the centralizer Varmsbear as they are set topivotal positions of adjustment.

The parts are controlled and held with the arms 34 in closed or openpositions by a spring assemblysurrounding the shaftl 28 in front ofthetrunnion plate 3|. "I'he 'assembly comprises a single spring 42interposedbetween vrespective front and rear washers 43 and 44. Thewasher 43 functions as a base for the assembly, being held against axialmovementalong the shaft by a two-piece ring 45 placed ini acircumferential grooveV 46 in the 'outer end of the shaft 28. The washer44 presses Vdirectly upon the trunnion lplate. 3| ina direction tomaintain the centralizer arms in contact with the guide or re- Thus, inrocking about their pivots to` and from' drill guiding positi0n,`the

`centralizer arms are opposed by the spring 42.

The spring yields as the trunnion plate 3| is cammed forward ,inresponse to the turning of the arms and then presses the yparts back tonormal as the rounded areas 4| pass themid- Together the concavesurfaces 35` Refer-Y point of their motion along the reaction plate. Thespring 42 acts yieldingly to maintain the arms in their effective orineffective positions. It is thought that the use of one large springfor positioning the centraliZer arms is -an improved construction, ascompared with the small spring plungers and detents ordinarily used forthis purpose.

The construction of the centralizer apparatus permits self-lubricationof the friction bearing surfaces therein. To this end a central bore 4lis formed in the shaft 2S of the centralizer body, which bore functionsas an oil reservoir. Lubri- `eating oil is'introduced into the reservoirthrough l a registering 'plug screw 4S in the plate 29.

a filler fport 48 V(see Fig. 3), normally closed by A port 5| conductsoil from the reservoir to the bore 26 and recess 46 where the end offeed screw .23 isjournaled. A series of ports 52 (see also Fig. y 4)radiate from the reservoir andopen,to theA exterior ofthevshaft at apoint surrounded by the@ trunnionplate 3|. The bearing surface uponwhich the trunnion plateslides is thus subject to continuous lubricationandthe movement'of the centralizer arms to and from effective positionAis unhindered. The Asurfaces of the'trunnions 32 receive oil throughpassages 53 in the trunnion plate, which passages register withV theports 5 2 at one ,point of the arm travel fromclosed to'open positions.i y

VInassembling the centraliser, the body portion 24iirstis"secured tothefront of the shell mount.

22"brytl'ieside rods 25,'lwith theend of the feed screfw K23 restinginfthebre 26. Then the plate 23 isfslipped overthestubshaft 23 and movedrearward thereon. Therecess 4|lis aligned with the b ore `2 6 andl isfitted on Ato the combination bushing'and V clovvelpin Y2, -as the.guide plate enlgages the-boss 30. The trunnionV plate 13|, with the twoarmslv34inr place on theutrunnionsw, follows the guide platefon theshaftA 28, and the lovvezredgesoff the centralizerarms are inserted inthe grooves 31.

The spring :assembly comprising springllzand Washers43 and 44 is thenmounted 'ontheouterl end of the body and locked in k placelbyfthe'ring,.45. ThepressureY ofthe spring," as exerted through the trunnionplate 3|, holdsfthewrcentralizer arms engaged in the gro`ovesv3'l Wand:resists turning movement of the arms "around, the trunnions 32. AcapScrew 54 closesV the" front ofthe reservoir bore 4l, and may beusedin conjunctionfwitha suitable yoke to compress thespring 42' topermit removal of the ring 45. .j Y

Preparatory to startingA adrilling operation the arms 34 "are adjustedto their upright or closedposition where they guide the drill steelas'it begins formation of the hole. As drilling progresses the drilladvances relatively tothe shellgand thev centralizer and, when thecentralizer arms 'have accomplished their function of directing thesteel'through the desired course Following retraction of the drill thearms may be returnedto upright position by-hand and so renderedeffective againrto guide the drill Steel.

- What isclaimed is: A r

l; A drill steel `centralizerV forv a rock drill adapted to advance-longitudinally during operation, comprisinga body portion, a, trunnionplate supportedby -said bodyfor'movement relative thereto, -meanscausing the Vmovement of said trunnion plate fto occur in a directionsubstantially parallel with the longitudinal axis ofjsaid "reges-354s?trunnion I plate and Vag'aii'rs arms bear inpivoting on sai'dipl'a'te,-andspring means *urgingsai'd trunnion plate in a directionsubstantially parallel with the longitudinal axis of said drill in orderto press said arms against said reaction means.

3. A drill steel centralizer according to claim 2, characterized in thatsaid spring means comprises a coil spring surrounding said stub shaftexteriorly of the trunnion plate.

4. A drill steel centralizer, comprising a body portion having aprojecting stub shaft, a plate slidable on said shaft, trunnions on saidplate angularly disposed with respect to each other and to said shaft,centralizer arms pivotally mounted on said trunnions, stationary angledjaws serving to guide said arms and having reaction surfaces againstwhich said arms bear in pivoting on said trunnions, a plurality ofangular faces on said arms brought selectively into cooperative relationwith said reaction surfaces by pivotal movement of said arms, springmeans urging said trunnion plate in a direction to press said arms intosaid angled jaws and thereby maintain said arms yieldingly in anyselected position of adjustment, and cam means on said arms moving saidtrunn ion plate against the pressure of said spring in response to thepivoting of said arms from one pivotal position to another.

5. A drill steel centralizer, comprising a body portion having aprojecting stub shaft, a plate slidable on said shaft, trunnions on saidplate 4 angularly disposed with respect to each other and to said shaft,centralizer arms pivotally mounted on said trunnions, stationary angledjaws serving to guide said arms, spring means acting on said plate topress said arms into said jaws, and reaction surfaces on said jawsagainst which said arms bear in pivoting on said trunnions.

6. A drill *steelv centralizer for a rock drill adapted to advancelongitudinally during operation, comprising a body portion having aprojecting stub shaft disposed in substantial parallelism with saiddrill, trunnions supported by said body portion and axially located in aplane spaced from, but substantially parallel to, the longitudinal axisof said drill, centralizer arms pivotally mounted on said trunnions, areaction plate surrounding said stub shaft and against which said armsbear in pivoting on said trunnions, said reaction plate and said armsbeing capable of re1- ative sliding movement determined by said stubshaft, complementary angled surfaces on said arms and said reactionplate brought selectively into cooperative relation by pivotal movementof said arms, and a spring surrounding said stub shaft exteriorly of thereaction plate and effecting a yielding engagement between said arms andsaid reaction plate.

7. A drill steel centralizerv for a rock drill adapted to advancelongitudinally during operation, comprising a body portion having aprojecti-ngl stub shaft disposed subs'tantlala4 parallelism with saiddrill, a trunnion plate on Usa-id -stlib 'f'.shaft, centralizer armsfpivotally-mountediorr said "trunnion plate, fa rea'ctionplate'onfsa'idstub -f'shaft Ydisposedfadjac'ent'to thev trunnion 'plate'- andKagainst-which said arms 'bear in pivotingfronv'said trunnion-- plate,yone 4of said-'plates being-slidable flcn'lgsaids'haftrelative to theother,` and jaispring l-surrounding said shaft -exteriorlyv'of'bothfof'lsaid 'i plates VAand Y pressing upon said movable plate toresist sliding movement-'thereof andA toimaintain A `-safid:arms Land`v'said y reaction plate in 'yielding #engagement j A 814i dr'ill steeljcentralizer `Yfor -a ro'cldri-ll *adapted t, advance long'itudinallynuringpperation,'-compr`sing afbcdy'portiont'having aproje'cting stubshaft disposed in substantial parallelism with said drill, a trunnionplate on said stub shaft having two spaced trunnions fixed thereon, thetrunnions on said plate being angularly disposed with respect to eachother and t'o said shaft but axially disposed in a common planesubstantially parallel to the longitudinal axis of said drill,centralizer arms pivotally mounted on said trunnion plate, a guide plateon said shaft and having angled jaws to receive said arms, one of saidplates being slidable along said shaft relative to the other,complementary angular surfaces on said arms and said guide plate broughtselectively into cooperative relation by pivotal movement of said arms,and spring means acting on'said movable plate to engage said arms insaid jaws and to maintain said arms yieldingly in a selected position ofadjustment.

9. A drill steel centralizer, comprising a, body portion having aprojecting stub shaft, a guide plate slidably mounted on said shaft', atrunnion l plate slidably mounted on said shaft, centralizer armspivotally mounted on said trunnion plate, grooved portions in saidguideplate to receive said arms, means including a spring pressing saidvplates together to maintain said arms` in said grooved portions,reaction surfaces on said guide plate against which said arms bear inpivoting on said trunnion plate, and a plurality of angular surfaces onsaid arms brought selectively into cooperative relation with saidreaction surfaces by pivotal movement of said arms and held in yieldingcontact with said surfaces by said spring.

10. A drill steel centralizer for a rock drill adapted to advancelongitudinally during operation, comprising a body portion having aprojecting stub shaft disposed in substantial parallelism with saiddrill, a guide plate slidably mounted on said shaft, a trunnion plateslidably mounted on said shaft exteriorly of said guide plate,centralizer arms pivotally mounted on said trunnion plate, reactionsurfaces on said guide plate against which said arms bear in pivoting onsaid trunnion plate, cam means effecting a separating movement of saidplates in response to pivotal movement of said arms, and spring meansexteriorly of said guide and trunnion plates for returning said elementsas said arms are moved into a selected position of adjustment,

11. A drill steel centralizer, comprising a body portion having aprojecting stub shaft, adjustable centralizer arms supported by saidbody portion, a centralizer arm control plate slidably mounted on saidstub shaft and movable thereon in response to adjustment of said arms, areservoir in said body portion containing lubricating oil, and portsleading from said reservoir to the exterior of said shaft at pointswithin the bearingsurace denedby the movement Qf Said conftrol plate. Yi Y. v A

12.* A drill steelcetreuzfr, eompisingebqy iportion having a `prm'ectingstub shaft, a trunnion plate slidably` mounted `on said Y stub shaft,

- centralizar arms pivotally mounted on said trunnion plate, meanseiectinga sliding movement of said trunnion plate alongsaidshaftinresponse to `pivotal movement of said arms, a reservoir insaid body portion containing lubricatingvoil, ports leading from saidreservoir to the exterior of said shaft at points Within thev bearingsurface deiined by the movement of saidtrunnion plate,and

Y ports 4in said trunnion plate leading fromthe inner periphery-thereof.to the exterior of the trunnions thereon andarranged to coincide withthe *ports in said stub shaft at one point of the travel of said plate.

13. In a rock drill assembly comprising adrill,

` a shell mount therefor, and. a-feed screw oper-

